currently its stock from 1970, it has never been replaced, I cut off the original muffler(it was quite rusty) and installed a used ANSA stacked double tip that I saved from a parts car I had. I will be putting on a MSA (Jethot coated)6 to 1 header, 2.25 exhaust pipe and still trying to figure out which stainless muffler to go with...